The present invention relates to the construction of a liquid crystal displaying device where two substrates (TFT substrate and counter substrate) are adhered with an adhesive sealant in the periphery thereof and a liquid crystal is interposed between these two substrates, and more particularly, to a liquid crystal displaying device where the photocuring adhesive sealant is applied, the positioning margin is designed to be smaller, and an aperture ratio is improved.
The liquid crystal displaying device is used in a wider field including the alternation of the CRT. Especially, carrying terminals such as note-book type PCs or systemized electronic note-books have been remarkably spread in recent years. When the liquid crystal displaying devices are used for the above described usages, lower power consumption is required. To achieve the lower power consumption, the aperture ratio of the liquid crystal displaying device is expected to be improved.
The normal thermosetting adhesive sealants have been used for many liquid crystal displaying devices, because they are superior to the other adhesive sealants in terms of moisture resisting property and bonding strength. But when the temperature differences are caused between the two opposing substrates (counter substrates), the positional deviation is caused due to the thermal expansion of the glass substrate, because heating is used for curing the sealant. To cope with the positional deviation, the margin of the positional deviation is adopted in pixel designing of the current liquid crystal displaying device. This design margin reduces the aperture ratio (ratio of the active area to the total area of the liquid crystal panel. The application of the photocuring adhesive sealant is becoming attractive as an art of reducing the design margin and manufacturing the liquid crystal displaying device high in aperture ratio. By the application of the photocuring adhesive sealant, the positional deviation margin can be designed to approximately one third, achieving the higher aperture ratio of the liquid crystal displaying devices.
However, any consideration of irradiating the light to the adhesive sealant is not adopted for the designing of the conventional liquid crystal displaying devices. When the photocuring adhesive sealant is used for the conventional liquid crystal displaying device using the thermosetting adhesive sealant, the inferior curing of the sealant is caused in a portion where the light is not irradiated. The photocuring adhesive sealant of non-curing is melted as and impurity in the liquid, thus resulting in inferior displaying. When the sealant is non-curing, the function as the bonding agent is not effective so that the two substrates cannot be adhered.
Thus, the design reference of the liquid crystal displaying device for using the photocuring adhesive sealant is required.
In the structure of the conventional liquid crystal displaying device using such a thermosetting adhesive sealant as described above, the inferior curing is caused when the photocuring adhesive sealant is used, because the use of photocuring adhesive sealant is not considered in the designed thereof, thus being unable to use for practical application. Although Japanese Unexamined Patent Publication No. 127174/1993, Japanese Unexamined Patent Publication No. 112128/1986, Japanese Unexamined Patent Publication No. 211396/1996, Japanese Unexamined Patent Publication No. 219932/1986, Japanese Unexamined Patent Publication No. 076930/1994, Japanese Unexamined Patent Publication No. 101395/1996, Japanese Unexamined Patent. Publication No. 146436/1996, and Japanese Unexamined Patent Publication No. 093421/1984 are used in the prior art where the photocuring adhesive sealant is used for the liquid crystal displaying device, the detailed description is not provided for the designing standard of the light shielding film where the adhesive sealant of the electrode substrate is positioned.,
In the present invention, the light necessary for curing the photocuring adhesive sealant can be applied sufficiently by slitting in the light shielding film where the photocuring adhesive sealant is positioned on the electrode substrate. Thus, a liquid crystal displaying device which can be prevented from the inferior curing of the photocuring adhesive sealant, and high in aperture ratio and high in reliability is obtained.
A first object of the present invention is to provide the structure of a novel liquid crystal displaying device for application of the photocuring adhesive sealant in a liquid crystal displaying device using the light shielding film.
The width of the light shielding film which exists above or under the photocuring adhesive sealant interposed by the electrode substrates is required to be 150 xcexcm or less.
The shape of the light shielding film existing above or under the photocuring adhesive sealant interposed by the substrates is required to be grid-shaped so as to transmit the light from the back face direction of the substrate (the reverse side of the film face).
The grid shape is required to be 150 xcexcm or lower in light shielding width and 5 xcexcm or more in the aperture width.
The shape of the light shielding film on the two substrates is grid-shaped designed to transmit the light from the back face side of the substrate (the reverse side of the film face), and the positional relation of the two opposing substrates is required to be 150 xcexcm or less in the superposing width (11 in FIG. 3) between the light shielding film portion of one of the two substrates and the light shielding film portion of another substrate.
The photocuring adhesive sealant which can be used in the present invention can be widely chosen if it is a material which starts the curing reaction by the light. Acrylate resin which can be used in the normal liquid crystal displaying device and resin or the like which uses photo cationic reaction can be used. Not only a material which cures only by the light, but a material which also has thermosetting property can be used.
Grid-shaped pattern examples which can be used in the present invention are shown in FIGS. 4, 5 and 6. The light shielding film portion, i.e., a light shielding portion in a grid-shaped pattern is shown with hatching, and the aperture portion, i.e, a portion for transmitting the light is shown with white painting. The shape of the white painting portion is not limited in the above although circle, ellipse or the like can be used in addition. Three types of square patterns 61, 62 and 63 are shown for illustration, and the pattern of FIG. 4 is used for detailed description. The width of the light shielding film to be defined in the present invention is denoted by X, and the aperture width is denoted by Y, wherein the width of the light shielding portion is X and the width of the aperture portion is Y in the figure.
The type of liquid crystal materials which can be used in the present invention is not limited. A liquid crystal material or the like can be used which is used for the normal TN type liquid crystal displaying device.
Normal glass, quartz or the like, and a substrate material which is used in the conventional liquid crystal displaying device can be used in the substrate material of the present invention. A metallic film of Al, Cr or the like and a multi-layer film of them, if these materials does not transmit light, can be used for the light shielding film material of the present invention.
The function of the present invention will be described using FIGS. 7 and 8. Reference numeral 101 is light, reference numeral 102 is an electrode substrate functioning as a substrate recited, reference numeral 103 is a light shielding film of 100 xcexcm width, reference numeral 104 is a light shielding film, reference numeral 105 is an electrode substrate functioning as a substrate, reference numeral 106 is a photocuring adhesive sealant, reference numeral 107 is a light shielding film of 800 xcexcm width, reference numeral 108 is a photocuring adhesive sealant, reference numeral 109 is a region, reference numeral 110 is an electrode substrate, and reference numeral 111 is a light passing through a photocuring adhesive sealant 106.
FIG. 7 shows a curing condition of a photocuring adhesive sealant 106 placed between the electrode substrate 102 where the light shielding film 103 of 100 xcexcm width is formed and an electrode substrate 105 where the light shielding film 104 is formed. The photocuring adhesive sealant 106 is completely cured with refractions of light 101 in the electrode substrate 102 and light 111 through reflection by the light shielding film 104.
FIG. 8 shows a curing condition of a photocuring adhesive sealant 108 placed between the electrode substrate 110 where the light shielding film 107 of 800 xcexcm width is formed and the electrode substrate 105 where the light shielding film 104 is formed.
Although the photocuring adhesive sealant in the lower portion of a light shielding film 107 of 800 xcexcm width is partially cured by the refractions or reflections of the light 101 as described above, it is not cured in the region 109. By examination, the width of the region 109 where the photocuring adhesive sealant is not cured is 650 xcexcm in this case. Namely, the curing depth of the light shielding depth is 75 xcexcm and the width of the light shielding film is required to be 150 xcexcm or less.
Lines and spaces (L/S) are formed on In constant period a glass substrate generally used in the TFTxe2x80x94LCD, a UV adhesive sealant is coated on the upper portion of the substrate and the adhesive sealant is squeezed to a thickness of 6 xcexcm with another glass substrate (with no pattern) of the same material as described above. Then, the UV light is irradiated from the reverse face side of the pattern and the adhesive sealant is cured. After the curing of adhesive sealant, the glass substrate is peeled away to measure the curing degree of the cured adhesive sealant. An analysis method used is the Frxe2x80x94IR. The results are shown in Table 1.
To sufficiently obtain the optical energies in the adhesive sealant for curing, the width of the aperture of the light shielding film is required to be 5 xcexcm or more.
To cure the photocuring adhesive sealant under the light shielding film, it is required to have 150 xcexcm or less in the width X of the light shielding film and 5 xcexcm or more in the width Y of the aperture.
Thus, a liquid crystal displaying device can be obtained which can prevent the photocuring adhesive sealant under the light shielding film from being inferior in curing, and is high in aperture ratio and high in reliability.